iOS and Android have been the Top to Smartphone OS and are head to head in all aspects of the game.

Security is a main concern and both have features like,

• Access controls, such as password, idle time locking and more
• Permission based Access Control, Granting each application a set of permission
• Limited hardware access, The apps cannot directly access hardware, this controlled by various layers of software architecture  which acts as intermediately
• Protection Against Web based attacks

Here is the comparison between Android and iOS, their Strength/Weaknesses features and more